I had a ghost update on my CIC account, and when I opened my application I found that my background status changed from "Your application is in progress. We will send you a message when we start your background check." to "We are processing your background check. We will send you a message if we need more information." on March 17, 2023. I called IRCC on March 17 and the agent told me that the background check has been completed. The background check status on IRCC Tracker is still "NOT STARTED" but I think it may get updated in the coming week.